The present disclosure relates to an optical information recording medium applied to a recordable optical disc, for example, and an optical information recording medium playback apparatus.
To date, optical discs for recording information or playing back recorded information using laser light have been put to practical use. For types of optical discs, there are a read-only type, a write-once type, and a rewritable type. In optical discs of the write-once type and the rewritable type, it is necessary for address information indicating a position on an optical disc to be recorded in advance for recording information.
For a method of recording address information, there are two types of methods that are familiar. One of the methods is to record address information as a pre-formatted pit. The other of the methods is to modulate a signal that forms a gutter, which is called a wobble, by address information. Recording a pre-formatted pit has a problem in that this reduces a user-data recording area, and thus decreases the recording capacity of an optical disc. The wobble method has an advantage because of having no such problem. In this regard, a gutter is referred to as a groove, and a track formed by a groove is called a groove track. A groove is defined as a part that is irradiated by laser light at the time of manufacturing an optical disc. An area sandwiched by adjacent grooves is referred to as a land, and a track formed by a land is called a land track.
When an address is recorded by wobbling, in order to further increase a recording capacity, it is desirable to use a method of recording data on both a groove track and a land track (suitably referred to as a land/groove recording method). In the land/groove recording method, it is possible to record address information for a groove track by deflecting laser light at the time of cutting. However, it is difficult to record an address for a land track by wobbling. When a land track is scanned, wobbles on both of the groove tracks are reproduced. Moreover, these wobbles represent information on different groove tracks, and the wobble phases are not aligned so that it is difficult to normally reproduce the wobbles.
Up to now, in the land/groove recording method, a proposal has been made of an optical disc that enables both of the addresses of a groove track and a land track to be reproduced. Japanese Unexamined Patent Application Publication No. 9-219024 has disclosed a method in which when an address is recorded in a groove track by wobbling, the address is recorded intermittently, and a phase of a recording position of the address is inverted between adjacent groove tracks. In this manner, when a wobble track is reproduced, address information that is originally recorded is intermittently reproduced, and when a land track is reproduced, addresses of the groove tracks that are adjacent on both sides are alternately reproduced. Accordingly, it is possible to obtain wobble information (address information) either at the time of scanning a groove or at the time of scanning a land.
In the techniques described in Japanese Unexamined Patent Application Publication Nos. 2003-178464 and 2006-228293, a land track and a groove track are individually wobbled, address information is recorded on one side wall of each track by the wobbling. Further, an address information block in a wobble track and an address information block in a groove track are disposed with being shifted in the track direction.